With the increased vigilance in infection control and the detection of new transmittable diseases, there is a need for disposable or single use biopsy forceps devices. Presently, the disposable and inexpensive biopsy forceps have jaws that may be made by either a casting method or through powder metal injection molding (MIM). Both methods can produce fairly inexpensive components, however due to the nature of the processes the biopsy jaws produced are of low quality. For instance the casting process does not produce jaws that have thin or very thin sections. This limitation reduces the capacity of the jaws and limits the size of the specimen that can be obtained. Furthermore, this method does not produce jaws that have sharp cutting edges and therefore does not have efficient biting capability. In U.S. Pat. No. 5,133,727 and related patents issued to Bales, Bales tried to overcome some of these problems by incorporating teeth at the cutting edge of the jaws. However, it is accepted in the industry that non-serrated, sharp jaws obtain better quality tissue specimen and provide for a better cut of the tissue, than jaws with the inclusion of teeth.
Jaws produced by MIM have thinner sections and sharper cutting edges, however the dimensional and geometrical repeatability of the parts is poor due to the extreme shrinkage of the parts during sintering process. Generally speaking, in order to produce precise jaws, one has to employ sophisticated CNC machining processes. However, these processes are prohibitively expensive for manufacturing single use instruments.
Prior art methods for manufacturing biopsy jaws have been developed to address some of the aforenoted problems, however these methods to do not disclose a method that produces biopsy forceps jaw with an improved cutting edge, is inexpensive to manufacture and is efficient to assemble. For example, U.S. Pat. No. 6,378,351 issued Apr. 30, 2002 to Ouchi, discloses a method for manufacturing a biopsy forceps cup for an endoscope in which a spoon-shaped forceps cup is formed by drawing a metal plate blank by a press. The method includes forming a first cut on the metal plate blank, wherein the first cut surrounds a contour of a portion of the metal plate blank defining a forceps cup blank corresponding to the forceps cup, the first cut being discontinued by a plurality of first connection portions. The method further includes forming a second cut on the metal plate blank, wherein the second cut surrounds the first cut, the second cut being discontinued by a plurality of second connection portions. The drawing operation on the metal plate blank is carried out while each of the first and second connection portions remain connected with respective neighbouring portions defined by each respective the first and second cuts. Ouchi clearly discloses the challenges and complexities of drawing a biopsy cup from a flat metal blank in a precise manner.
U.S. Pat. No. 5,707,392 issued Jan. 13, 1998 to Korntenbach discloses a hermaphroditic biopsy forceps jaws for use in an endoscopic biopsy forceps instrument made from a flat sheet of stainless steel or other suitable material which is stamped and then progressively formed into a jaw cup having a tang. According to the preferred embodiment of the invention, the jaw is provided with two substantially parallel tangs, one being shorter than the other. Both tangs are provided with central mounting holes for mounting the jaw on an axle pin between the arms of a clevis. The longer of the tangs is provided with a hole for coupling it to the distal end of a control wire. The tangs are located such that when the jaws are mounted in the clevis, the short tang of each jaw resides between the two tangs of the other jaw. The stamped jaw of the invention may be provided with or without teeth. The location of the tangs permits the mounting of a knife between the jaws, if desired. Other end effectors of similar construction are also disclosed. The method disclosed in Kortenbach however has limited precision as the profile of the cup of the jaw is first cut and then drawn/formed to a spoon like shape.
Furthermore, the prior art has not been able to overcome the following challenges and problems illustrated in FIGS. 1–6, so as to produce or manufacture precise biopsy forceps jaws that have edges that closely match edge to edge when the jaws are in the closed position: overbite where one jaw is longer than the other; lateral shift caused by poor repeatability of the thickness of the arm of the jaw and/or its location; incorrect positioning of the pivot hole in relation to the plane of the cutting edge resulting in a large gap on both sides of the jaws when the tips of the cups meet, but the backs do not; or when the backs of the jaws meet, but the tips do not; a gap created when the cutting edge of the jaws meet on one side but not on the opposite side resulting from poor control of the perpendicularity of the cutting plane of the jaws to the arm, or a twist of the cup versus the arm; gaps between the jaws as a result of irregular cutting planes and or cutting edges; and/or a combination of any or all of the above mentioned problems.
Thus a method of manufacturing a stamped biopsy forceps jaw that produces inexpensive yet high quality biopsy jaw forceps that have precise matching of the jaw during closing and obtains excellent quality tissue samples and overcomes the problems outlined above is desirable.